The Famatinian Orogen Along the Protomargin of Western Gondwana: Evidence for a Nearly Continuous Ordovician Magmatic Arc Between Venezuela and Argentina

Ramos, Víctor A.

doi:10.1007/978-3-319-67774-3_6

Cited by 38 publications

(28 citation statements)

References 68 publications

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“…During the late Neoproterozoic-to-early Cambrian, the Pampean orogeny affected the eastern part of the study area between 27° S and 33° S, the area that is now known as the Sierras Pampeanas (e.g., Rapela et al 1998). A further four subsequent major orogenies have been identified during the Paleozoic, these being (1) the early Ordovician Famatinian orogeny, (2) the middle-late Ordovician Ocloyic orogeny, (3) the late Devonian-early Carboniferous Chanic orogeny, and (4) the early Permian San Rafael orogeny (for reviews of these orogenies, see Heredia et al 2018;Ramos et al 2018;Rapela et al 2018). The Famatinian orogeny resulted in the establishment of a magmatic arc along the western margin of Gondwana, vestiges of which still exist today in the centralwestern part of the Sierras Pampeanas (Ramos et al 2010).…”

Section: Geologic Settingmentioning

confidence: 99%

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Piceda

Scheck‐Wenderoth

Dacal

et al. 2020

Int J Earth Sci (Geol Rundsch)

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The southern Central Andes (SCA) (between 27° S and 40° S) is bordered to the west by the convergent margin between the continental South American Plate and the oceanic Nazca Plate. The subduction angle along this margin is variable, as is the deformation of the upper plate. Between 33° S and 35° S, the subduction angle of the Nazca plate increases from sub-horizontal (< 5°) in the north to relatively steep (~ 30°) in the south. The SCA contain inherited lithological and structural heterogeneities within the crust that have been reactivated and overprinted since the onset of subduction and associated Cenozoic deformation within the Andean orogen. The distribution of the deformation within the SCA has often been attributed to the variations in the subduction angle and the reactivation of these inherited heterogeneities. However, the possible influence that the thickness and composition of the continental crust have had on both short-term and long-term deformation of the SCA is yet to be thoroughly investigated. For our investigations, we have derived density distributions and thicknesses for various layers that make up the lithosphere and evaluated their relationships with tectonic events that occurred over the history of the Andean orogeny and, in particular, investigated the short- and long-term nature of the present-day deformation processes. We established a 3D model of lithosphere beneath the orogen and its foreland (29° S–39° S) that is consistent with currently available geological and geophysical data, including the gravity data. The modelled crustal configuration and density distribution reveal spatial relationships with different tectonic domains: the crystalline crust in the orogen (the magmatic arc and the main orogenic wedge) is thicker (~ 55 km) and less dense (~ 2900 kg/m3) than in the forearc (~ 35 km, ~ 2975 kg/m3) and foreland (~ 30 km, ~ 3000 kg/m3). Crustal thickening in the orogen probably occurred as a result of stacking of low-density domains, while density and thickness variations beneath the forearc and foreland most likely reflect differences in the tectonic evolution of each area following crustal accretion. No clear spatial relationship exists between the density distribution within the lithosphere and previously proposed boundaries of crustal terranes accreted during the early Paleozoic. Areas with ongoing deformation show a spatial correlation with those areas that have the highest topographic gradients and where there are abrupt changes in the average crustal-density contrast. This suggests that the short-term deformation within the interior of the Andean orogen and its foreland is fundamentally influenced by the crustal composition and the relative thickness of different crustal layers. A thicker, denser, and potentially stronger lithosphere beneath the northern part of the SCA foreland is interpreted to have favoured a strong coupling between the Nazca and South American plates, facilitating the development of a sub-horizontal slab.

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Section: Geologic Settingmentioning

confidence: 99%

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Piceda

Scheck‐Wenderoth

Dacal

et al. 2020

Int J Earth Sci (Geol Rundsch)

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“…• From the late Neoproterozoic until middle-late Devonian times, the Famatinian orogenic cycle affected the entire proto-Pacific margin of South America, from Venezuela to Argentina (Ramos 2018b). In the Central Andes, metamorphic rocks and orthogneisses with Famatinian ages were identified within the northern part of the Eastern Cordillera of Peru, where the orogen was controlled by the old Grenvillian sutures.…”

Section: Geological Backgroundmentioning

confidence: 99%

Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods

2019

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The Huayna Potosi, Zongo and Taquesi are Triassic plutons located at the core of the Real Cordillera of Bolivia. In this paper, several Rb-Sr and K-Ar ages obtained in the past at the São Paulo Geochronology Laboratory, yet unpublished, will be presented, along with newer U-Pb Sensitive High-Resolution Ion Microprobe (SHRIMP) determinations made in the same laboratory, allowing us to redefine the geologic history of this part of the Central Andes. Rb/Sr analyses of some low grade metapelitic country rocks of the early Paleozoic (Amutara and Cancañiri Formations) yielded a Rb-Sr isochron age of 344 ± 38 Ma, indicating the action of an early Gondwanide regional event. A five-point Rb-Sr isochron from a granite outcrop of the Huayna Potosi pluton yielded an age of 224 ± 28 Ma. In addition, an important Ar loss in micas was detected in the Zongo granitoids and their country rocks, recording a thermal event that opened this isotopic system in the Oligocene. Newer U-Pb SHRIMP zircon ages of ca. 221 Ma were obtained in two other granitic outcrops of the Huayna Potosi granite. They confirmed its Triassic crystallization age, and a similar U-Pb SHRIMP age of 221.9 ± 1.5 Ma was obtained for one sample of the Taquesi pluton. For the Zongo pluton, many of the zircon grains obtained from one sample of its Kuticucho facies yielded extremely high uranium content, which produced reverse discordant apparent ages. However, due to the fair alignment of the analytical points in the Concordia diagram, possibly corresponding to a linear correlation, we made a regression calculation and the interception of the Concordia curve resulted in a rather imprecise age of 220 ± 20 Ma. Our conclusion was that the final magmatic crystallization and the intrusion of plutons in the central part of the Cordillera Real of Bolivia have occurred close to 221.5 ± 2.0 Ma, in late Triassic times. Finally, the U-Pb SHRIMP ages obtained in inherited zircon xenocrysts from the four available granitic rocks yielded very different ages, and many of them are related to previous magmatic episodes of the Andean Tectonic System. A few other age measurements indicated sources related to much older Proterozoic magmatic events associated with rocks from the Andean basement.

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“…The basement of the Altiplano is interpreted as the Arequipa Terrane (for extent and boundaries of this terrane, see Ramos, 2008). The partial detachment of this terrane from the Amazonian Craton led to the development of a large retroarc basin of Ordovician to Devonian strata known as the Central Andean Basin (Sempere, 1995;Bahlburg et al, 2006;Ramos, 2018).…”

Section: Geographical and Geological Settingmentioning

confidence: 99%

First evidence of Lower–?Middle Ordovician (Floian–?Dapingian) brachiopods from the Peruvian Altiplano and their paleogeographical significance

Colmenar

Hodgin

2020

J. Paleontol.

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The lower strata of the Umachiri Formation from the Altiplano of southeast Peru have yielded a brachiopod-dominated assemblage, containing representatives of the brachiopod superfamilies Polytoechioidea, Orthoidea, and Porambonitoidea, as well as subsidiary trilobite and echinoderm remains. Two new polytoechioid genera and species, Enriquetoechia umachiriensis new genus new species and Altiplanotoechia hodgini n. gen. n. sp. Colmenar in Colmenar and Hodgin, 2020, and one new species, Pomatotrema laubacheri n. sp., are described. The presence of Pomatotrema in the Peruvian Altiplano represents the occurrence at highest paleolatitude of this genus, normally restricted to low-latitude successions from Laurentia and South China. Other polytoechioids belonging to Tritoechia (Tritoechia) and Tritoechia (Parvitritoechia) also occur. Identified species of orthoids from the genera Paralenorthis, Mollesella, and Panderina? occur in the Peruvian Cordillera Oriental and in the Argentinian Famatina Range. The only porambonitoid represented is closely related to Rugostrophia latireticulata Neuman, 1976 from New World Island, interpreted as peri-Laurentian. These brachiopod occurrences indicate a strong biogeographic affinity of the Peruvian Altiplano with the Famatina and western Puna regions, suggesting that the brachiopod faunas of the Peruvian Altiplano, Famatina, and western Puna belonged to a well-differentiated biogeographical subprovince during the Early–Middle Ordovician on the margin of southwestern Gondwana. Links with peri-Laurentian and other low-latitude terranes could be explained by island hopping and/or continuous island arcs, which might facilitate brachiopod larvae dispersal from the Peruvian Altiplano to those terranes across the Iapetus Ocean. Brachiopods from the lower part of the Umachiri Formation indicate a Floian–?Dapingian age, becoming the oldest Ordovician fossils of the Peruvian Altiplano. UUID: http://zoobank.org/9670a000-260d-4d75-9261-110854c7afb8

show abstract

The Famatinian Orogen Along the Protomargin of Western Gondwana: Evidence for a Nearly Continuous Ordovician Magmatic Arc Between Venezuela and Argentina

Cited by 38 publications

References 68 publications

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Lithospheric density structure of the southern Central Andes constrained by 3D data-integrative gravity modelling

Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods

First evidence of Lower–?Middle Ordovician (Floian–?Dapingian) brachiopods from the Peruvian Altiplano and their paleogeographical significance

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